JPH0585516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a shaft support mechanism for a pulling rotation shaft in a single crystal growth apparatus using the Czyochoralski method.

[Conventional technology]

The single crystal growth method using the Czyochoralski method is
The raw material is melted in a crucible, a seed single crystal attached to the tip of a pulling shaft is brought into contact with the melt, and the single crystal is gradually pulled up while rotating the pulling shaft to grow a large single crystal under the seed crystal. It is widely used for growing single crystals of various materials.

In recent years, in such single crystal growth, automatic growth methods using weight sensors have become common because it is necessary to control the diameter of the single crystal to a desired size in order to improve yield. This weight sensor can be used to measure the amount of loss of raw material in the crucible, but in many cases it is attached to the pulling rotation shaft to directly detect the weight of the grown crystal and measure the amount of weight increase per unit time. I try to do that. The signal from this weight sensor is directly compared with a preset weight program, or converted into diameter and compared with a preset shape program, and the difference is fed back to the crucible heating means to control the weight or shape. It is.

By the way, when attaching a weight sensor to a lifting rotation shaft, if the lifting shaft is supported in the usual way, noise will be introduced into the weight signal due to contact, etc., so the pulling shaft is rotated without intermediate support. Therefore, wobbling of the pulling shaft is unavoidable. In addition, this is not a problem if the crystal can be grown in the atmosphere, but when growing crystals that require adjusting the atmosphere, the seal between the chamber covering the growth area and the pulling shaft may be incomplete. This is one of the reasons why the growing conditions become unstable.

[Problem to be solved by the invention]

An object of the present invention is to provide a single crystal growth apparatus that can effectively prevent the wobbling of the pulling shaft, completely isolate the chamber from the outside air, and still be able to measure the crystal weight with high accuracy. There is a particular thing.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a pulling rotating shaft with a double structure consisting of a pulling shaft and a hollow rotating shaft that accommodates the pulling shaft, a weight sensor is attached to the upper part of the hollow rotating shaft, and the weight sensor is mounted on the upper part of the hollow rotating shaft. The pulling shaft is suspended from the shaft, and the pulling shaft is supported by a linear ball bearing provided inside the hollow rotating shaft, and the radial bearing and thrust are connected at the part where the hollow rotating shaft penetrates into the chamber covering the single crystal growth area. It is unique in that it is supported by a combination of bearings.

〔Example〕

FIG. 1 is a diagram conceptually showing the main parts of the single crystal growth apparatus of the present invention, with some parts cut away and locally shown in cross-section. A crucible, a crucible heating means, a crucible heat retaining means, etc. (not shown) are housed in the chamber 1, and a pulling rotation shaft 2 penetrated into the chamber 1 is moved up and down by a stage 3 that is moved up and down by a drive mechanism provided on a support (not shown). The stage 3 is connected to a motorized reduction gear 4 similarly provided on the stage 3 via drive gears 5 and 6.

The above-mentioned lifting rotation shaft 2 has a double structure of a rotation shaft 7 having a hollow interior and a pulling shaft 8 housed in the hollow rotation shaft 7, and a weight sensor is attached to the upper cover 9 of the hollow rotation shaft 7. 10 is attached, the weight sensor 10
The above-mentioned pulling shaft 8 is suspended from the shaft, and the pulling shaft 8 is mounted on a linear ball bearing 11 provided inside the hollow rotating shaft 7.
It is supported by a, 11b, and 11c. The lifting rotation shaft 2 is attached to the stage 3 via a stage bearing 12, while the portion where the lifting rotation shaft 2 penetrates into the chamber 1 is attached to a thrust bearing 13.
and a radial bearing 14.
It is supported by 5.

[Effect]

According to the above structure, the pulling shaft 8 penetrates into the chamber 1 while being protected by the hollow rotary shaft 7 supported by linear ball bearings 11a, 11b, and 11c and guided by a combination bearing 15.
It can effectively prevent wobbling. Moreover, the pulling shaft 8
is stationary with respect to the hollow rotating shaft 7, and since the operating direction of the linear ball bearing 11 coincides with the direction of the single crystal load, the single crystal load can be faithfully transmitted to the weight sensor 10 without resistance.

In this way, the device of the present invention prevents the pulling shaft from wobbling, making it possible to measure the crystal weight with high accuracy, but this structure also completely isolates the chamber from the outside air. It is also suitable for For such purpose, it is only necessary to cover the upper part of the pulling rotation shaft 2 with a sealing cover 16 and to provide a stage seal 17 and a chamber mouth seal 18. Also, the chamber 1 is attached to the sealing cover 16.
If the same gas used inside the chamber 1 is introduced from the inlet 19 and the pressure is made equal to the internal pressure of the chamber 1, it is possible to prevent the gas from moving inside the hollow rotary shaft 7.

The electrical signal from the weight sensor 10 is inputted to a data processing device, computer, etc. (not shown) via a signal line 20, a slip ring 21, a slip ring signal line 22, and a connector 23, and a feedback signal is extracted.

〔Effect of the invention〕

As described above, according to the present invention, the fluctuation of the pulling shaft can be completely suppressed, the chamber can be completely isolated from the outside air, and the crystal weight can be measured with high accuracy. It has extremely good effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram conceptually showing the main parts of the single crystal growth apparatus of the present invention. 1... Chamber, 3... Stage, 7... Hollow rotating shaft, 8... Pulling shaft, 10... Weight sensor, 11... Linear ball bearing, 13...
Thrust bearing, 14...Radial bearing.

Claims (1)

[Claims] 1 In a weight detection type automatic single crystal growth apparatus in which a weight sensor is attached to the pulling rotation shaft, the pulling rotation shaft has a double structure consisting of a pulling shaft and a hollow rotation shaft that houses the pulling shaft, and A weight sensor is attached to the upper part of the hollow rotating shaft, a pulling shaft is suspended from the weight sensor, the pulling shaft is supported by a linear ball bearing provided in the hollow rotating shaft, and the hollow rotating shaft is used for single crystal growth. A single crystal growth apparatus characterized in that the part that penetrates into the chamber that covers the part is supported by a bearing that is a combination of a radial bearing and a thrust bearing.